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首页> 外文期刊>Monthly Notices of the Royal Astronomical Society >From radio-quiet to radio-silent: low-luminosity Seyfert radio cores
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From radio-quiet to radio-silent: low-luminosity Seyfert radio cores

机译：从无声到无声：低发光塞弗特无线电核心

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摘要

A strong effort has been devoted to understand the physical origin of radio emission from low-luminosity AGNs (LLAGNs), but a comprehensive picture is still missing. We used highresolution (<= 1 arcsec), multifrequency (1.5, 5.5, 9, and 14 GHz) NSF's Karl G. Jansky Very Large Array (VLA) observations to characterize the state of the nuclear region of ten Seyfert nuclei, which are the faintest members of a complete, distance-limited sample of 28 sources. With the sensitivity and resolution guaranteed by theVLA-A configuration, we measured radio emission for six sources (NGC 3185, NGC 3941, NGC 4477, NGC 4639, NGC 4698, and NGC 4725), while for the remaining four (NGC 0676, NGC 1058, NGC 2685, and NGC 3486) we put upper limits at tens mu Jy beam(-1) level, below the previous 0.12 mJy beam(-1) level of Ho & Ulvestad (2001), corresponding to luminosities down to L <= 10(19) WHz(-1) at 1.5 GHz for the highest RMS observation. Two sources, NGC 4639 and NGC 4698, exhibit spectral slopes compatible with inverted spectra (alpha = 0, S-nu proportional to nu(-alpha)), hint for radio emission from an optically thick core, while NGC 4477 exhibits a steep (+ 0.52 +/- 0.09) slope. The detected sources are mainly compact on scales = arcseconds, predominantly unresolved, except NGC 3185 andNGC3941, in which the resolved radio emission could be associated to star formation processes. A significant X-ray -radio luminosities correlation is extended down to very low luminosities, with slope consistent with inefficient accretion, expected at such low Eddington ratios. Such sources will be one of the dominant Square Kilometre Array (SKA) population, allowing a deeper understanding of the physics underlying such faint AGNs.
机译：为了了解低发光度AGN（LLAGN）的无线电发射的物理起源，已经做出了巨大的努力，但是仍然缺乏全面的了解。我们使用高分辨率（<= 1 arcsec），多频（1.5、5.5、9和14 GHz）NSF的Karl G.Jansky超大型阵列（VLA）观测来表征十个塞弗特核的核区域状态。距离有限的完整样本（28个来源）的最微弱成员。利用VLA-A配置保证的灵敏度和分辨率，我们测量了六个源（NGC 3185，NGC 3941，NGC 4477，NGC 4639，NGC 4698和NGC 4725）的无线电发射，而其余四个源（NGC 0676，NGC） 1058，NGC 2685和NGC 3486），我们将上限设为几十微米的Jy光束（-1），低于Ho＆Ulvestad（2001）以前的0.12 mJy光束（-1），对应于低至L <对于最高RMS观测值，在1.5 GHz时= 10（19）WHz（-1）。 NGC 4639和NGC 4698这两个信号源均显示出与倒置光谱兼容的光谱斜率（alpha = 0，S-nu与nu（-alpha成正比）），暗示了光学较厚核的无线电发射，而NGC 4477则显示出陡峭的（ + 0.52 +/- 0.09）斜率。除NGC 3185和NGC3941（其中分辨出的无线电发射可能与恒星形成过程有关）外，探测到的源主要在比例尺=弧秒上紧凑，主要是未解析的。在如此低的爱丁顿比下，显着的X射线-放射性发光度相关性延伸到非常低的发光度，其斜率与吸积效率低下一致。这样的源将成为占主导地位的平方公里阵列（SKA）之一，从而可以更深入地了解此类微弱AGN的物理基础。

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  • 来源
    《Monthly Notices of the Royal Astronomical Society》 |2019年第3期|3185-3202|共18页
  • 作者

    Chiaraluce E.; Bruni G.; Panessa F.; Giroletti M.; Orienti M.; Rampadarath H.; Vagnetti F.; Tombesi F.;

  • 作者单位

    INAF, Ist Astrofis & Planetol Spaziali, Via Fosso Caveliere 100, I-00133 Rome, Italy|Univ Roma Tor Vergata, Dipartimento Fis, Via Ric Sci 1, I-00133 Rome, Italy;

    INAF, Ist Astrofis & Planetol Spaziali, Via Fosso Caveliere 100, I-00133 Rome, Italy;

    INAF, Ist Astrofis & Planetol Spaziali, Via Fosso Caveliere 100, I-00133 Rome, Italy;

    INAF, Ist Radioastron, Via Gobetti 101, I-40129 Bologna, Italy;

    INAF, Ist Radioastron, Via Gobetti 101, I-40129 Bologna, Italy;

    Univ Manchester, Sch Phys & Astron, Jodrell Bank, Ctr Astrophys, Turing Bldg,Oxford Rd, Manchester M13 9PL, Lancs, England;

    Univ Roma Tor Vergata, Dipartimento Fis, Via Ric Sci 1, I-00133 Rome, Italy;

    Univ Roma Tor Vergata, Dipartimento Fis, Via Ric Sci 1, I-00133 Rome, Italy|Univ Maryland, Dept Astron, College Pk, MD 20742 USA|NASA, Goddard Space Flight Ctr, Xray Astrophys Lab, Greenbelt, MD 20771 USA|INAF, Osservatorio Astron Roma, Via Frascati 33, I-00044 Rome, Italy;

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  • 正文语种 eng
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  • 关键词

    techniques: interferometric; galaxies: active; galaxies: nuclei; galaxies: Seyfert; radio continuum: galaxies; X-rays: galaxies;

    机译：技术：干涉测量;星系：活跃;星系：核;星系：塞耶特;无线电连续管：星系;X射线：星系;

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